Audio

Audio Global Viewpoint – February 2018

Basic EQ For Broadcast Voices

By Frank Beacham, 3 weeks ago

All audio recordings of human voices occasionally need tweaking. Whether you’re a reporter doing a voice-overs, a podcaster or a broadcast narrator, everyone is recording more on-location these days. From reducing minor background noise to compensating for poor room acoustics, minor adjustments in equalization (EQ) can enhance the human voice.

Start by recognizing that every audible sound sits within the
frequency range of human hearing. With equalization, one can adjust the
character and tone of a sound by boosting or cutting these different
frequencies.

It’s important to remember that sound can’t be
completely changed with equalization. One can’t create new frequencies.
We can only remove or exaggerate what’s already there. EQ allows one to
accentuate or attenuate specific parts of a sound.

A broadcast equalizer limiter is an application that often relies on software and a user GUI to enable on-screen frequency sliders to make changes in the overall quality of music or voice recordings you are trying to broadcast. Click to enlarge.

However, EQ can improve the clarity of the human voice or reduce some
unwanted characteristics picked up in the original recording. EQ can be
very complex, but non-technicians don’t have to understand the entire
subject to use it to their benefit. Just a few minor EQ tweaks can make
major improvements in voice quality.

The basic EQ plug-in that
comes with most digital audio workstations is all that’s needed. These
plug-ins can correct most common problems, including traffic noise,
wind, background machinery or handling noise with a microphone. All of
these problems occur in the low-frequencies, which can often be eliminated by reducing specific frequencies in the lower part of the audio spectrum.

Low-cut filters attenuate frequencies below the cut-off and high-pass filters allow frequencies above the cut-off to pass without attenuation. As an example, rumble filters used on record players use a low-cut filter and have an adjustable cut of frequency between 10Hz and 200Hz. Although its referred to as low-cut, it is still technically high-pass, but we call it low-cut due to the low frequency of the cut-off point. If the low-cut frequency is too low then it will not reduce the rumble, but if it’s too high then it could affect the lower end of the audio mix.

Shelves
attenuate or boost everything above or below a certain frequency by a
set amount. A high shelf set to 10kHz with a boost of +3dB will boost
everything above 10kHz by 3dB. A low shelf would do the opposite.Turning
up the low can warm the audio, while lowering it can enhance the
clarity.

A parametric equalizer lets the user control three aspects of the audio: level (boosting or cutting), the center frequency, and bandwidth (also known as Q or quotient of change) of each frequency. Such precision gives users more control over sound modification. Click to enlarge.

Parametric EQ can make very specific adjustments in the audio. It is
best used for targeting a particular frequency to eliminate. It might be
like an “S” with too much whistling sound or excess room resonance.
Parametric EQ allows one to boost or cut any frequency using bell
curves, filters and shelves.

With EQ, there are no absolute rules.
But it is best to start by making cuts rather than boosts. EQ can throw
you. Boosting one frequency range can cut other frequencies, and
vice-versa.

For example, cutting the low-end can make the high-end
sound brighter. So, listen carefully as adjustments are made. Adding or
cutting one frequency can impact the audio in ways we don’t expect. In
most cases, gentle cuts or boosts, of only a few dB, will sound best.
Leave serious acoustic problems for the experts.

Wide curves (low
Q) and small boosts or cuts will sound most natural. After EQ
adjustments have been made, be sure to play the audio and turn the EQ on
and off while the audio is playing. It’s important to make sure the EQ
is actually improving the sound.

Even studio audio recordings can benefit from post-production audio processing.

Finding the right EQ settings requires experimenting. However, there
are some common places to begin. If a recording sounds dull or boomy,
reduce the frequencies around 100-200 Hz with a low shelf or a wide
parametric EQ. If the the recording is shrill, try reducing the setting
around 1000 Hz with a parametric EQ.

If a speaker’s “S” sounds
stand out, it can be lessened with a narrow-shaped curve using a
parametric EQ. The targeted frequency to cut varies widely among different
brands and types of speakers, ranging from around 3 kHz up to 7 kHz,
depending on how the speaker pronounces the “S” sound.

After very
minor EQ adjustments are complete, the voice-over narrator need to make
sure there is no clipping in the segment. If it’s a problem, a little
limiting might be needed. Limiting also adds some extra perceived
volume, which can enhance the voice.

Software-based audio processing often comes in the form of plug-ins. When combined they offer a tremendous range of options for audio control and adjustment. Click to enlarge.

For those with thin voices, one way to sound richer and more
authoritative is to use a ribbon microphone and make use of its
proximity effect by speaking closer. This can ensure that “voice of God
effect” used by on-air talent since the 1930s. It can boost the on-air
effect of any voice by adding gravitas.

Of course, there is no exact science
to improving on-air voices. Everyone has to experiment to find what’s
right for them. But minor EQ and mic adjustments can enhance virtually
voice. It just requires minor tweaking to find the sweet spot.

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